Had a call where the mgr got on an E2 controller and graphed a couple of 8 foot produce multidecks and saw that the discharge air being graphed would go up to 43 degrees a times before it swung back down to 33. He was worried about health inspectors, although this pair of cases never got dinged before. So I found that both cases were run off on mech stat under the case b and one liquid line solenoid valve. The stat was set on 30. Not sure where the bulb was. I checked the discharge air with a k type lead and it was indeed a 10 degree differential. The product was 35 to 37 degrees. I find this normal and acceptable and explained to the mgr that the discharge is not always what the product was and when reading a graph the middle point is likely product temp, the middle of the diff. I turn the stat down approx 1 degree and left. Please let me know your thoughts on what I could have done or what I did was enough. This was an old small market.
Why is it controlling with a stat when you've got an E2?
Not to jump the thread, but I just recently lost an account, based partly on just that situation. Store Brass got REAL uptight when I found the Multi-Deck Meat and the Dairy line-ups (two separate systems mechanically) scabbed onto one A419 hiding under a meat case, and told them it would cost $X to properly seperate them & place back on RMCC. Some people's kids, I guess.
Originally Posted by jpsmith1cm
If it is a Rack system and on an E2 with temp sensors there should be no reason the cases would be controlled with a Tstat, unless there is other cases on that Ckt with a colder SST?
They are just using the e2 to control defrost and monitor temps. It's not on a rack, it's got a single condenser on the roof, full site glass btw. The e2 does run a rack as well, but it is another suction group. They have in house guys and a lot of their stuff is pieced together.
I've seen any number of cases that have temp controllers in the raceways, but are supposed to be on Rack control. Usually the controllers in the raceways are set slightly COOLER than the rack controller is calling for. This is considered an emergency back up control, just in case the rack controller loses control for whatever reason. Not uncomm, but has tripped up many techs. Myself included. Good find bud.
Originally Posted by wrightbrigade
Just cause a store has an E2 and sensors monitoring case temperatures, does not mean that it's actually controlling anything :)
I have several stores that just monitor temperatures and dial out alarms.
With defrost controlled by gang timers and cases controlled through EPR or Liquid Line Solenoid with stats.
It's also common for Combo systems such as (A1,2,3,4,5) to have mechanical controls at the cases t-stats and timers.
Or as engineerdave says, many times there is EMS control with the mechanical controls left in as backup's
Markets require a thorough investigation as to what is controlling the case...ESPECIALLY after several remodels!
Never know what you're gonna find :)
Originally Posted by Phase Loss
Ain't that the truth.